A breeding colony of healthy uniform marmosets of the genera Callithrix and Saguinus has been developed in an indoor-outdoor environment for utilization in biomedical research and teaching at Texas A&M University and other institutions. The overall aim of the project is to establish a self-sustaining colony of marmosets with maximum reproduction. To this end, the specific goals of the project are: 1) to establish and maintain a self-sustaining colony of 100 breeding pair of marmosets, 2) to characterize marmoset wasting (chronic wasting syndrome) and determine control methods, and 3) to describe and determine the incidence of congenital defects in the colony. "Wasting marmoset syndrome" is being evaluated and efforts are being made to determine if it is related to immunodeficiency, malabsorption and/or nonutilization of nutrients. The types and incidence of congenital malformations in infants born into the colony is being determined. Behavior studies aimed at improved breeding efficiency and adaptability of the animals for basic research have also been initiated.